All window treatments are designed for three major functions: the control of light, energy efficiency and the aesthetic effect of room decor. There are two basic types of window shades which are light filtering and room darkening. Light filtering window shades are made of translucent materials that allow some light to enter the room and offer some privacy, while room darkening window shades are made from opaque materials and offer complete room darkening characteristics. The room darkening window shade remains the best window treatment for sleeping areas or where complete privacy is desired.
One of the major problems with the window shade is that, as a single source of light control, the user is limited to the type of window shade that is installed. Light filtering shades are not good in areas where darkening of the room is desired and room darkening shades cannot offer good partial light control.
Another major problem is that the window shade is not normally looked at as a decorative window treatment. Manufacturers of the more fashionable venetian blinds, mini blinds, and all types of pleated shades have tried to introduce room darkening variations of their products with little success. The basic construction of venetian blinds and pleated shades is such that they require holes for the operating cords and these holes allow light to pass through. Furthermore, the venetian blind slats, while attempts have been made to redesign their configuration, also let light pass through where the slats overlap when in the closed position.
Window shades are unsurpassed in their ability to control the loss of heating or cooling energy. The cloth or vinyl material used to make window shades provide a solid energy barrier while venetian blinds and pleated shades, because of the openings in their construction, are less effective in this area.
Window shades, venetian blinds, mini blinds and pleated shades are manufactured both by custom fabrication (made to fit a specific consumer's window) or in standard stock sizes. The stock venetian and mini blind products are stocked by the retailer in most sizes from 23 inches through 36 inches, or longer, every inch on the inch. The design of these products allows them to fit windows within a range of approximately 3/4 inch from the size purchased.
For example, a 29 inch stock sized mini blind will fit a window opening from 283/4 inches to 291/2 inches, the mounting bracket allows for this adjustably. This allows the consumer to buy a standard size and adjust the product when it is installed in the window. Window shades are normally stocked by the retailer in only three or four sizes and are cut to the consumer's exact dimensions, using a special machine, at the time of purchase.
While it is apparent that the combination of the window shade and venetian blinds or pleated shades would provide the ultimate window treatment, the construction of most windows make it difficult or impossible to install two separate bracketing systems which would allow the combination of the decorative treatment and the functionality of the roller window shade.